380 ALGiE FROM CKNTRAL AFRICA. 



[=0. gotlandicum Wittr. v. Cambrense Turn. Desmid Notes, Natu- 

 ralist, Nov. 1893, 345, fig. 7] in the different inclination of the 

 inferior lateral margins, the longer superior lateral margins, and 

 the narrower apex. 



22. C. globulatum, nov. sp. (Figs. 7-8). C. minutum, 1^-plo 

 longius quam latum, profunde constrictum, sinu lineari extreme 

 subampliato ; semicellulae semicirculares angulis basalibus leviter 

 rotnndatis ; a vertice visae circulares ; membrana crassa, minute 

 punctata. Long. 17 /t ; lat. 13-5 /x; lat. isthm. 4-5 /x. Mwangadan 

 River, S. of Fuladoga. 



It differs from C. affine Racib. (Desm'uhja iv podrdzy na okolu 

 ziemi, Krakow, 1892, 3, tab. vi. fig. 25) in its deeper constriction, 

 its much narrower sinus, its thicker membrane, and circular 

 vertical view. 



23. C. subvenustum, nov. sp. (Fig. 17). C. parvum, paullo 

 longius quam latum, subprofunde constrictum, sinu lineari ; semi- 

 cellulre late truncato-pyramidat^, angulis rotundatis, lateribus tri- 

 undulatis, apicibus retusis ; a vertice viste elliptica? ad medium 

 utrobique tumore prasditre ; a latere visae late pyramido-ovats ; 

 membrana punctata. Long. 36-5 /x ; lat. 32-5 /i; lat. isthm. 15 n; 

 crass. 22 /x. Mwangadan River, S. of Fuladoga. 



This differs from 0. venustnm (Breb.) Arch. [= C. Cawhricuin 

 Cke. & Wills] in its much broader cells, its broader isthmus, and 

 in the median tumours of the vertical view. 



24. Staurastrum nephroideum, nov. sp. (Fig. 13). S. par- 

 vum, paullo longius quam latum, profunde constrictum, sinu 

 angusto extremo subampliato extrorsum valde aperto ; semicellulre 

 subreniformes, dorso multe convexo ; a vertice vistB triangulares 

 lateribus concavis, angulis subtruncatis ; membrana subcrassa 

 densissime punctata. Long. 38 /a; lat. 35 /x; lat. isthm. 11'5 /x. 

 Mwangadan River, S. of Fuladoga. 



25. S. subdilatatum, nov. sp. (Fig. 16). S. parvum, paullo 

 longius quam latum, profunde constrictum, sinu aperto extremo 

 rotundato ; semicelluhie elliptico oblonga>, apicibus subtruncatis ; a 

 vertice visa? triangulares, lateribus concavis, angulis rotundatis ; 

 membrana dense et delicate granulata. Long. 26-5-27'5 /x; lat. 

 23-25 /x; lat. isthm. 9-5 /x. Mwangadan River, S. of Fuladoga. 



This Staurastrum appears to be nearest to S. dilatatum Ehrnb., 

 from which it differs in being relatively longer in proportion to its 

 breadth, and in having more numerous granules, which are not 

 arranged in transverse series across the angles. 



Pediastre^. 



26. Pediastrum Boryanum (Turp.) Menegh. ; Ralfs, Brit. Desm. 

 187, tab. 31, fig. 9. 



Var. granulatum (Kiltz.) A. Br. Forma cellulis periphericis 

 processibus delicatissimis instructis. Diam. cell, peripher. 18-21 /x. 

 Mwangadan River, S. of Fuladoga. 



